The purpose of the proposed research is an in depth investigation into the structural, physiological and biophysical properties of the cell surfaces of lymphocyte subpopulations. Lymphocyte populations will be separated based on anatomical origin, functional properties and characteristics. Cell membranes will be labelled with radioisotopes and labelled membrane proteins analyzed for size, charge, hydrophobic properties, antigenicity and ligand binding ability. Turnover and shedding rates of membrane components will be assessed as well as the fate of membrane component anti-membrane component ligand complexes. Modes of analysis will include disc electrophoresis in polyacrylamide gels, isoelectric focussing and serological precipitation of membrane components. Electron spin resonance spectroscopy will be employed to determine the physical state of membrane lipids, the effect of membrane binding ligands on lipid fluidity and membrane lipid changes during cell-mediated cytolysis.